This invention is in the field of impacting devices for drill bits.
It has been known to provide means for periodically impacting a drill bit at the bottom of a well to assist in cutting the earth formation. See, for example, the patents to Grant et al., U.S. Pat. No. 1,748,341, Snyder, U.S. Pat. No. 2,742,265, and Stilley, U.S. Pat. No. 2,400,853. In the Grant patent a multiplicity of drill chisels are vertically slidable in a holder rotatable relative to the drill string. A cam on the drill string periodically lifts the chisels one at a time, and springs then urge the chisel downwardly to impact the earth formation. The chisel holder is held against rotation by the chisel bits that remain in contact with the well bottom.
The patent to Snyder employs a separate hammer rotatable and slidable on a rotary driver and has vanes to resist rotation as the drill string rotates. The hammer is provided with a cam engageable with a cam carried by the rotatable driver and which periodically lifts the hammer, then drops the same onto the drill bit.
The patent to Stilley employs a plurality of chisel bits or blades vertically slidable and spring pressed upwardly against a cam driven by a turbine in a housing at the bottom of the drill string. Thus, the turbine periodically projects the drill chisel downwardly against the formation to facilitate drilling.